1. Field of the Invention
This invention generally relates to an apparatus for processing input data (hereunder referred to as an input data processor), and more particularly, to an input data processor for use in an electronic musical instrument and which performs a predetermined processing of input data when a quantity of a change of input data exceeds a predetermined threshold value indicated by another preliminarily input parameter (hereunder referred to as change border data).
2. Description of the Related Art
A conventional input data processor for use in an electronic music instrument is applied, for example, to a pitch bender in which a sliding contact of a variable resistor is connected to a rotary bending lever or a bending wheel, and a constant voltage is applied across the variable resistor. Namely, when the bending lever or the bending wheel is moved, a contact position to which the sliding contact is connected is changed, and as a result, a fraction of the constant voltage obtained from the sliding contact is also changed. Thereafter, an analog signal indicating the thus-obtained fraction of the constant voltage (i.e., analog input data) is converted into a digital signal, and a pitch of a musical tone sounded by the electronic musical instrument is changed by the input data processor according to a quantity of a change of the digital input data indicated by the digital signal.
Such an input data processor is also applied to a modulation wheel, an expression foot pedal, a balance controller, a Pan Pot controller, a volume controller, a tempo controller, a system for sensing a touch on a key of a keyboard, and a system for detecting an effect depth, etc., in addition to the pitch bender.
Nevertheless, in the conventional input data processor, a resolution of a detection of a change of the input data (i.e., a minimum unit to be used for representing a quantity of a change of the input data to be detected) always has a fixed value; i.e., the resolution is not changed regardless of the value of the input data. Note, however, that in practice, the detection of a change of a value of the input data for some range of values of the input data, should be performed with high precision (i.e., with a small resolution), but for another range of values of the input data, the detection may be effected with a low precision (i.e., with a large resolution). For example, in the case of the pitch bender, by which the pitch of a musical tone to be sounded by the electronic musical instrument is made higher or lower than that preliminarily indicated by an operator or user, the detection of a change of the input data in the vicinity of the preliminarily indicated pitch must be made with a small resolution. Conversely, in ranges of pitches sufficiently distant from the preliminarily indicated pitch, the detection may be effected with a large resolution.
In such a case, if the resolution is not changed regardless of the value of the input data, the small resolution used for the detection in the vicinity of the preliminarily indicated pitch, is naturally employed and thus even in the ranges of pitches sufficiently distant from the preliminarily indicated pitch, the detection is effected with the small resolution. Accordingly, an efficient detection of a change of the input data cannot be achieved with the conventional input data processor.
The present invention is intended to eliminate the foregoing drawback of the prior art, and accordingly, an object of the present invention is to provide an apparatus for processing input data, which apparatus can efficiently detect a change of the input data by changing the resolution of the detection according to the value of the input data.